Numerous devices for dispensing a cleaning and/or disinfectant solution into a toilet tank for flow into a toilet bowl when the tank is flushed are known. These devices can be characterized as active dispensers, wherein valves or other mechanisms are used to initiate flow from the dispenser when the toilet tank is emptied to a given level, or as passive dispensers, wherein no moving parts are employed, the discharge of a predetermined amount of solution from the dispenser being actuated solely by the lowering of the height of the water contained in the tank.
Exemplary of the former class, i.e., active dispensers, are devices described in U.S. Pat. Nos. 1,307,535 to Ciancaglini, 2,692,165 to Sinkwich, 3,341,074 to Pannutti, 3,698,021 to Mack, et al., 3,778,849 to Foley, 4,036,407 to Slone and 4,244,062 to Corsette. A disadvantage of these active-type dispensers is a tendency for the valve or other mechanical actuating means to become clogged, and thus fail in the open or closed position. Passive-type dispensers overcome this particular problem inasmuch as there are no moving parts that can fail to operate in the proper manner.
In one type of passive dispenser, the dispenser is alternatively flooded when the tank is filled and emptied, at least partially, by siphoning therefrom when the tank is flushed. For example, U.S. Pat. No. 650,161 to Williams, et al., discloses a dispenser comprising a product chamber, a vent extending upwardly from the top of the product chamber, and an inverted U conduit that operates to siphon the concentrated solution of disinfectant from said chamber when the tank is emptied. The Williams, et al., device is intended to reside at the bottom of the tank, the outlet of the inverted U conduit being proximate thereto. U.S. Pat. Nos. 969,729 to Smith, 1,144,525 to Blake, and 1,175,032 to Williams, et al., and British Pat. Nos. 10,110 (1907) to Holloway, 21,253 (1908) to Berry and 11,469 (1890) to Fleuss each disclose dispensers adapted to withdraw a given volume of solution from the product chamber through a siphon conduit in response to a lowering of the tank liquid level.
Each of the dispensers described above are in the form of a jar, bottle, or other container that resides at the bottom of the tank. It is preferred, however, for the convenience of the user, to provide a toilet tank dispenser adapted for suspension from the rim of the tank. For example, U.S. Pat. No. 2,839,763 to Newsom shows a passive dispenser attached to the rim of a toilet tank, the rising tank water causing disinfectant to be dispensed into the tank water. In the present invention, however, the disinfectant is dispensed into the tank water upon a lowering of the level of same, the objective being to maximize retention of the concentrated cleaning solution, although in diluted form, in the bowl of the toilet.
U.S. Pat. No. 4,438,534 to Keyes, et al. discloses a passive dispenser adapted to codispense a concentrated detergent solution and a concentrated disinfectant solution from separate product chambers, and preferably is further adapted to be suspended from the rim of the toilet tank. A disadvantage with the dispenser of the Keyes, et al. patent when same is suspended from the tank rim is that solution issuing from the product chambers commences with the tank water level substantially above the bottom of the tank. Hence, a portion of the solution thus released is not retained in the toilet bowl, but rather is carried through the bowl to the sewer.
U.S. Pat. No. 4,305,162 to Cornelisse, Jr., et al., discloses a toilet tank dispenser adapted for suspension from the tank rim and of the type wherein an air lock is formed in the siphon conduit, which dispenser is an improvement of the dispenser disclosed in U.S. Pat. No. 4,208,747 to Dirksing. According to Cornelisse, Jr., et al., product solutions at times ought to be discharged at a relatively slow rate, and it would thus be possible that the tank would begin to refill with water prior to completion of the discharge operation. If the tank refilled up to the inlet/discharge port of the siphon tube before completion of discharge, there would be no way of forming the air bubble required to obtain the air lock in the siphon tube. Cornelisse, Jr., et al., retards discharge of the solution from the dispenser by enlarging the lower end of the longer leg of the siphon tube and providing a properly sized orifice therein that communicates with the tank water. In the discharge cycle an air bubble is retained within the lower end of the longer leg, which air bubble is available to form the air lock should the tank water rise above the leg before all solution has drained therefrom.
While this construction of Cornelisse, Jr., et al. will retard flow of solution from the dispenser, it does not prevent flow from starting as soon as the tank water level has fallen to below the upper vent means proximate the top of the dispenser. Hence, the concentrated solution is dispensed into the tank water as the level passes through essentially the entire height of the dispenser, a portion of which passes through the bowl and is ineffectual. Furthermore, the improvement disclosed in the Cornelisse, Jr., et al., patent is not very effective in the case of low viscosity and/or low surface tension solutions inasmuch as that improvement does not control the onset of dispensing, but rather the rate of dispensing.
U.S. Pat. No. 3,778,849 to Foley describes an active dispenser which considers the problem of dispensing product solution late in the flush cycle. The Foley dispenser comprises a product chamber, a first conduit entering the product chamber, and a second conduit in fluid communication with the first conduit. The upper end of the first conduit is proximate with the top of the dispenser and is provided with a first check valve to permit air to leave but not enter the conduit, while the lower end of the first conduit is in the body of liquid and is provided with a U-bend having a second check valve that permits liquid to leave but not enter the conduit. Fluid communication between the first conduit and the product chamber is provided by means of an orifice proximate the bottom of the product chamber. The second conduit, which is above the orifice and extends downwardly a substantial distance into the body of liquid, provides fluid communication between the product chamber and the body of liquid.
As with many active dispensers, failure of the check valves may occur. A second disadvantage is that the Foley dispenser requires a conduit that extends far into the tank. Accordingly, a single device is not suitable for placement in the myriad of tank styles and sizes available.